The production and characterisation of spray dried nanoporous microparticles (NPMPs) intended for dry powder inhalation drug delivery systems

Abstract

The focus of the research presented in this thesis was on the potential application of a novel spray drying method to produce excipient-free nanoporous microparticles (NPMPs) of bioactive drug compounds and co-spray dried drug-excipient systems by a one-step spray drying technique. The potential of these NPMPs for inclusion in drug delivery systems, with particular emphasis on dry powder formulations for pulmonary drug delivery, was explored. A range of ten sulfa compounds: sulfadiazine, sulfadimidine, sulfadimethoxine, sulfadoxin, sulfaguanidine, sulfamerazine, sulfamethizole, sulfamethoxazole, sulfanilamide and sulfathiazole, as well as three steroid drugs: betamethasone base, prednisolone and prednisone and one anti-asthmatic drug, sodium cromoglicate, were selected for analysis. In all cases the physicochemical characteristics of the unprocessed, spray dried non-porous and porous powders were studied, which included amorphous/crystalline nature, thermal behaviour, polymorphic form and residual solvent content. A systemic evaluation of the micromeritic properties of the powders was undertaken and included particle size, particle morphology, powder density, specific surface area and flowability. The aerodynamic assessment of fme particles was evaluated using the Andersen cascade impactor. Solid-state stability studies of NPMPs were undertaken.